1. Field
The embodiments generally relate to cellulosic fibers with odor controlling characteristics. More particularly, the embodiments relate to cellulosic fibers impregnated with an odor-controlling formulation. The embodiments further relate to a method for applying the odor-controlling agent to cellulosic fibers. Cellulosic fibers produced according to the embodiments are suitable for use in a wide variety of absorbent articles intended for body waste management such as undergarments for those suffering from incontinence, feminine shields, baby diapers, bedding products such as mattress pads and covers, wipes, and medical gowns. The embodiments also provide a process of manufacturing an absorbent article comprising the cellulosic fiber of the embodiments.
2. Description of Related Art
Cellulosic fibers are used in a wide variety of personal care products. These range from absorbent articles such as personal hygiene products to wipes or pads used in medical and food handling applications. While the design of personal care products varies depending upon intended use, there are certain elements or components common to such products. For instance, absorbent articles intended for personal care, such as adult incontinent pads, feminine care products, and infant diapers typically are comprised of at least a top sheet, a back sheet, and an absorbent core. The absorbent core is typically comprised of cellulosic fibers and superabsorbent materials distributed among the fibers.
Designers of absorbent articles have generally designed products responsive to consumer demands for less bulky, and less expensive absorbent articles having a high absorption rate and high capacity. As a result, absorbent article designs have become progressively thinner, using various absorbent polymers with high absorptive power. For example, the thickness of a feminine hygiene pad has been reduced from about 15 mm to 20 mm in the mid 1980's to about 2.5 mm to 6 mm today. In addition, absorbent article designs have incorporated other materials to improve absorbency and efficiency of the product, such as, for example, an acquisition-distribution layer, typically located between the top sheet and the absorbent core, to accelerate liquid acquisition times, and reduce product wetness.
In recent years product designers have shifted their design focus to addressing aesthetic and skin-wellness issues, including the removal of unpleasant odors, and the prevention of skin diseases such as dermatitis, rash and redness caused by wearing a disposable absorbent article for a relatively long time. It is believed that the unpleasant odors in an absorbent article originate from numerous sources including bodily fluids such as urine and menses absorbed by the absorbent articles. Degradation of the components present in these fluids (e.g., protein, fat, etc.) can generate malodorous byproducts. In addition, urine and/or other exudates usually contain microorganisms that produce the urease enzyme that is responsible for the degradation of urea present in urine to ammonia. The ammonia, in turn, has the potential to cause dermatitis, rash and/or other forms of skin irritation. For an infant, these conditions can be a serious medical issue which, in extreme cases, can result in death.
There have emerged two general categories of absorbent article technologies for removal of odors and improvement of skin wellness: (1) odor absorption technology; and (2) anti-microbial treatment technology. The odor absorption technology includes incorporation into the absorbent article of compounds that are known to absorb odors, such as activated carbons, clays, zeolites, silicates, cyclodextrine, ion exchange resins and various mixture thereof as for example described in EP-A-348 978; EP-A-510 619, WO 91/12029; WO 91/11977; W089/02698; WO 91/12030; WO 94/22501; WO 99/06078; and WO 01/48025 (the contents of each of these applications is incorporated herein by reference in their entirety). For example, a relatively recent and widely used odor absorbing agent for odor control is cyclodextrin. Cyclodextrins are ring-shaped sugar molecules with a hydrophilic surface and an empty hydrophobic cavity. Cyclodextrins, like other odor absorbing agents, control odor by mechanisms whereby the malodorous compounds and their precursors are physically absorbed by the agents. The agents thereby hinder the exit of the malodorous compounds from absorbent articles. However, such mechanisms are not completely effective because the formation of the odor itself is not prevented, and thus some odor still may be detected in the product. Also, it is believed that the odor absorbing particles lose odor-trapping efficiency when they become moist, as most absorbent articles do. Furthermore, in order for these reagents to be effective at controlling odor, a high loading of these reagents is required which increases the cost of the absorbent article, and tends to adversely affect the absorbency and performance of the absorbent article.
The second category of odor-removal and skin wellness technology involves introducing anti-microbial agents into the absorbent article either by physical or chemical methods. An example of such approach is described in patent WO99/32697 (which is incorporated herein by reference in its entirety), which discloses coating a nonwoven fabric of hydrophobic material (e.g., polypropylene fibers) with an anti-microbial agent chitosan and chitin-based polymers. The anti-microbial agent is applied to the surface of the fabric, and the resulting treated fabric is used as a diaper liner to reduce odor and promote skin wellness. It is believed, however, that such technology is very limited in preventing odor formation, since the anti-microbial agent is located outside the body fluid accumulation zone—i.e., the absorbent core of the absorbent article.
The use of an anti-microbial agent in an absorbent article also is described in Japanese Patent No. 4-17058 (incorporated herein by reference in its entirety). This patent discloses a disposable diaper that is said to prevent the occurrence of diaper rash caused by certain bacteria such as colibacillus and Candida and to inhibit the production of ammonia (formed by hydrolysis of the urea contained in the urine) by bacteria. The disclosed disposable diaper consists of a water-permeable top sheet, a water-impermeable back sheet, and a water-absorbent layer sandwiched between these sheets. The water-absorbent layer has an ammonia-adsorbent and a water-absorbent polymer that contains an anti-microbial agent such as benzalkonium chloride and/or chlorhexidine gluconate.
It is believed, however, that using surfactant-based anti-microbial agents or bactericides poses some disadvantages. One drawback is that surfactant-based anti-microbial agents tend to reduce the absorbency and the wettability of the absorbent layer, thereby causing a significant re-wet or leakage problem in absorbent article. It is also believed that surfactant-based anti-microbial agents are only effective in reducing certain bacterial activity, and have only limited anti-microbial properties.
The description herein of certain advantages and disadvantages of known odor-reducing and anti-microbial agents for use in absorbent articles, and methods of their preparation, is not intended to limit the scope of the present invention. Indeed, the present invention may include some or all of the methods and materials described above without suffering from the same disadvantages.